Re: PCI memory mapping

Alan Cox (alan@lxorguk.ukuu.org.uk)
Sat, 4 Sep 1999 16:54:15 +0100 (BST)

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> I am working on a PCI device driver in Linux.
> I am trying to map 128MB PCI memory space to virtual address of Pentium
> CPU.
> I am observing that ioremap() call returns only PAGE ALIGNED virtual
> address. My device driver requires the virtual address to be 128MB
> aligned! (I need the virtual address start in the form - xxxx x000 0000
>
> 0000 0000 0000 0000 0000 (given in binary x-dont care).
>
> How do I ensure it in Linux? Can anybody help me?

You need to fix your driver. The physical alignment which matters for
many devices is handled by PCI itself. Virtual alignment requirements are
driver bugs ..

Alan

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